Databases Shared Among Multiple Users
Follow these rules for databases that are shared among multiple users:
• Have users use only application programs to access data in the database. Discourage users from using Ingres tools, such as a terminal monitor or VDBA, to access data. Permitting users to access data only by means of an application program guarantees that the executing queries were written by an application programmer and are not ad hoc queries that can damage or delete data, or cause lock contention delays.
• Ensure that reports are run with readlock=nolock (see
READLOCK=NOLOCK Option). You can do this by including all reporting tools in application programs and setting readlock there, or by running all reports from operating system scripts, which set lockmode before the report runs. Doing this avoids locking contention problems that can lead to severe concurrent performance problems in the database.